Apparatus

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sensors Mode-S transponder

A1B519

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N209SY · EMBRAER ERJ-170-200 (long wing) · operated by SKYWEST AIRLINES INC

Hex
A1B519
Octal
50332431
Decimal
10,597,657
Country
US
Tail
N209SY
Type
E75L
No current signal · last broadcast Jul 26, 22:15 UTC
Flights observed
649
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:15 UTC

Last known position

Most recent position reported by Mode-S A1B519.

Country allocation

The ICAO 24-bit address A1B519 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 20 distinct

Callsign Airline Flights Last seen
SKW5468 - 8 2026-07-16
SKW5798 - 7 2026-07-13
SKW5994 - 6 2026-06-30
SKW5823 - 6 2026-07-20
SKW5593 SkyWest Airlines 6 2026-07-26
SKW5504 - 6 2026-06-19
SKW5414 - 6 2026-07-13
SKW5301 - 6 2026-06-27
SKW6014 - 5 2026-07-24
SKW6005 - 5 2026-06-19
SKW6004 - 5 2026-07-12
SKW5937 - 5 2026-07-05
SKW5871 SkyWest Airlines 5 2026-07-21
SKW5756 - 5 2026-07-08
SKW5531 - 5 2026-07-15
SKW5525 SkyWest Airlines 5 2026-07-26
SKW5434 - 5 2026-07-06
SKW5407 SkyWest Airlines 5 2026-06-08
SKW5396 - 5 2026-06-29
SKW5324 - 5 2026-07-15

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SKW5260 SFO → SNA Jul 26, 21:40 UTCJul 26, 22:15 UTC35m
2026-07-26 SKW5765 SFO → BOI Jul 26, 19:40 UTCJul 26, 20:20 UTC40m
2026-07-26 SKW5525 DEN → MKE Jul 26, 17:15 UTCJul 26, 18:30 UTC1h 15m
2026-07-26 SKW5593 DEN → SBP Jul 26, 15:14 UTCJul 26, 16:11 UTC57m
2026-07-26 SKW5820 MAF → DEN Jul 26, 11:20 UTCJul 26, 12:30 UTC1h 10m
2026-07-26 SKW5820 MAF → DEN Jul 26, 11:23 UTCJul 26, 12:28 UTC1h 5m
2026-07-25 SKW415P ORD → BUF Jul 25, 23:50 UTCJul 26, 01:05 UTC1h 15m
2026-07-25 SKW5654 SUN → ORD Jul 25, 19:50 UTCJul 25, 22:05 UTC2h 15m
2026-07-25 SKW5654 SUN → ORD Jul 25, 19:43 UTCJul 25, 21:34 UTC1h 51m
2026-07-25 SKW5473 SNA → SFO Jul 25, 16:45 UTCJul 25, 18:55 UTC2h 10m
2026-07-24 SKW5623 ORD → BHM Jul 24, 18:20 UTCJul 24, 21:20 UTC3h 0m
2026-07-24 SKW5623 ORD → BHM Jul 24, 18:23 UTCJul 24, 21:03 UTC2h 40m
2026-07-24 SKW6014 - Jul 24, 15:35 UTCJul 24, 17:10 UTC1h 35m
2026-07-24 SKW4724 BFL → SFO Jul 24, 13:10 UTCJul 24, 13:55 UTC45m
2026-07-24 SKW4737 FAR → DEN Jul 24, 07:05 UTCJul 24, 07:45 UTC40m
2026-07-24 SKW5339 SAV → ORD Jul 24, 04:15 UTCJul 24, 05:20 UTC1h 5m
2026-07-24 SKW5650 SFO → SNA Jul 24, 00:40 UTCJul 24, 01:50 UTC1h 10m
2026-07-23 SKW5938 FCA → SFO Jul 23, 22:15 UTCJul 23, 23:25 UTC1h 10m
2026-07-23 SKW4757 ORD → ASE Jul 23, 18:45 UTCJul 23, 21:05 UTC2h 20m
2026-07-23 SKW5898 SGF → DEN Jul 23, 15:50 UTCJul 23, 17:25 UTC1h 35m
2026-07-23 SKW5898 SGF → DEN Jul 23, 15:52 UTCJul 23, 17:16 UTC1h 24m
2026-07-23 SKW5886 DEN → SGF Jul 23, 02:45 UTCJul 23, 04:20 UTC1h 35m
2026-07-23 SKW5886 DEN → SGF Jul 23, 02:50 UTCJul 23, 04:17 UTC1h 27m
2026-07-22 SKW5429 ONT → SFO Jul 22, 23:10 UTCJul 23, 01:30 UTC2h 20m
2026-07-22 SKW5429 ONT → SFO Jul 22, 23:03 UTCJul 23, 01:11 UTC2h 8m
2026-07-22 SKW5340 ORD → LGA Jul 22, 19:40 UTCJul 22, 20:35 UTC55m
2026-07-22 SKW5525 DEN → MKE Jul 22, 17:00 UTCJul 22, 18:05 UTC1h 5m
2026-07-22 SKW5525 DEN → MKE Jul 22, 17:01 UTCJul 22, 18:02 UTC1h 1m
2026-07-22 SKW5593 DEN → SBP Jul 22, 14:30 UTCJul 22, 15:40 UTC1h 10m
2026-07-22 SKW5390 MSO → SFO Jul 22, 00:20 UTCJul 22, 02:00 UTC1h 40m
2026-07-21 SKW5871 LEX → ORD Jul 21, 22:05 UTCJul 21, 23:05 UTC1h 0m
2026-07-21 SKW5871 LEX → ORD Jul 21, 21:48 UTCJul 21, 23:03 UTC1h 15m
2026-07-21 SKW4746 - Jul 21, 19:00 UTCJul 21, 19:55 UTC55m
2026-07-21 SKW4648 MBS → ORD Jul 21, 16:25 UTCJul 21, 17:05 UTC40m
2026-07-21 SKW5715 - Jul 21, 13:30 UTCJul 21, 14:20 UTC50m
2026-07-21 SKW5785 ORD → DTW Jul 21, 01:20 UTCJul 21, 02:05 UTC45m
2026-07-20 SKW5334 - Jul 20, 21:25 UTCJul 20, 23:10 UTC1h 45m
2026-07-20 SKW5449 ORD → HPN Jul 20, 17:40 UTCJul 20, 19:40 UTC2h 0m
2026-07-20 SKW5449 ORD → HPN Jul 20, 17:53 UTCJul 20, 19:39 UTC1h 46m
2026-07-20 SKW5823 OKC → ORD Jul 20, 13:55 UTCJul 20, 15:40 UTC1h 45m
2026-07-20 SKW4727 DEN → MKE Jul 20, 03:50 UTCJul 20, 05:00 UTC1h 10m
2026-07-20 SKW4727 DEN → MKE Jul 20, 03:43 UTCJul 20, 04:59 UTC1h 16m
2026-07-19 SKW5544 - Jul 19, 23:00 UTCJul 20, 01:05 UTC2h 5m
2026-07-19 SKW4802 DEN → MKE Jul 19, 19:55 UTCJul 19, 21:50 UTC1h 55m
2026-07-19 SKW4804 DTW → ORD Jul 19, 16:55 UTCJul 19, 18:00 UTC1h 5m
2026-07-19 SKW4809 ORD → ICT Jul 19, 14:23 UTCJul 19, 15:39 UTC1h 16m
2026-07-19 SKW4809 ORD → ICT Jul 19, 14:20 UTCJul 19, 15:45 UTC1h 25m
2026-07-19 SKW5500 ROA → ORD Jul 19, 11:05 UTCJul 19, 12:35 UTC1h 30m
2026-07-18 SKW5405 - Jul 18, 23:55 UTCJul 19, 01:50 UTC1h 55m
2026-07-18 SKW5623 ORD → BHM Jul 18, 19:00 UTCJul 18, 22:00 UTC3h 0m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the N209SY page for operator, model, and routing details .

Mode-S A1B519 frequently asked

What is Mode-S code A1B519?
A1B519 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N209SY.
Where is Mode-S A1B519 registered?
Mode-S code A1B519 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A1B519 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1B519, octal 50332431, decimal 10,597,657.
What flights does A1B519 operate?
Mode-S A1B519 has broadcast 20 distinct callsigns, including SKW5468, SKW5798, SKW5994, SKW5823, SKW5593.